Currently, radio mobile communication systems are evolving toward their fourth generation (that is, 4G network). The evolution to 4G, for example, promises a considerable increase in system requirements which is a so-called mobility increase in addition to increase of the number of users and a user bandwidth. Several new technologies are expected to be used to satisfy the increase in the system requirements. Two of these technologies are OFDMA (Orthogonal Frequency Division Multiple Access) and multicarrier transmission, and both are proposed in WiMAX 2.0 (IEEE 802.16m) and 3GPP (3rd Generation Partnership Project) LTE-Advanced (Long Term Evolution Advanced).
OFDM (Orthogonal Frequency Division Multiplexing) is a multiplexing technique that subdivides a bandwidth into a plurality of frequency subcarriers. In the OFDM system, an input data stream is divided into several parallel substreams with a lower data rate (accordingly, increased symbol duration), and the respective substreams are modulated with separate orthogonal subcarriers to be transmitted. The increased symbol duration improves the robustness of the OFDM with respect to the channel delay spread. Further, introduction of a cyclic prefix (CP) is able to completely remove intersymbol interference so far as the CP duration is longer than the channel delay spread. Further, the OFDM modulation may be realized by an efficient inverse fast Fourier transform (IFFT) that makes a plurality of subcarriers usable with little complexity. In the OFDM system, resources are usable in a time domain by OFDM symbols, and in a frequency domain by subcarriers. The OFDMA is a multiple access scheme that performs multiple operations of data streams from the plurality of users to the time and frequency resources.
The multicarrier transmission uses two or more radio frequency carriers (RF carriers) to exchange data between a base station (BS) and a plurality of mobile stations (MS). According to IEEE 802.16m system description document (SDD), the respective mobile stations are controlled by RF carriers that are called primary carriers [see IEEE 802.16m SDD, IEEE 802.16m-08/003r7, February, 2009 (Non-Patent Literature 1), p. 144]. Additional RF carriers may be defined and used in order to improve the user experience and the quality of service (QoS). Further, the additional RF carriers may be configured and optimized for a specific service. These additional RF carriers are called secondary carriers.
In a multicarrier operation, in the same manner as the single carrier operation, a single MAC (Media Access Control) PDU (Protocol Data Unit) or a connection MAC PDU is received through a PHY (Physical Layer) SAP (Service Access Point), and thereafter, FEC (Forward Error Correction) blocks that are called PHY PDU are formed. The PHY generates a single modulation symbol sequence that is considered as a single hybrid ARQ (HARQ: Hybrid Automatic Repeat Request) packet by executing channel encoding, modulation, and MIMO (Multiple Input Multiple Output) encoding for the PHY PDU. According to IEEE 802.16m SDD (see Non-Patent Literature 1, p. 143), in the OFDMA multicarrier operation, the modulation symbol sequence of the PHY PDU may be transmitted in two styles as below.
1. The modulation symbol sequence is transmitted with any one of the plurality of RF carriers (primary or secondary carriers). Here, different PHY PDUs that are transmitted with the same or different RF carriers may have different MCS (Modulation and Coding Schemes) and MIMO schemes.
2. In using the same MCS and MIMO schemes, by data-segmenting and mapping on different RF carriers, the modulation symbol sequence is transmitted in DRUs (Distributed Resource Units) that are carried over several RF carriers.
In this description, as a method of transmitting a modulation symbol sequence of the PHY PDU in the OFDMA multicarrier operation, a case of using the second method is presupposed.
According to IEEE 802.16m SDD (see Non-Patent Literature 1, p. 72), the DRU is a kind of LRU (Logical Resource Unit) that includes a group of subcarriers that spread across the entire bandwidth of a single RF carrier. The LRU is a basic logical unit for allocating resources, the LRU is a subcarrier of 18×Nsymy, and here, Nsym is the number of OFDMA symbols per subframe. The LRU includes pilots, and thus the effective number of subcarriers in the LRU depends on the number of allocated pilots. FIG. 17 is a diagram exemplifying an LRU 1500 in the OFDMA multicarrier operation. In FIG. 17, the number of OFDMA symbols is Nsym=6. Accordingly, LRU 1500 corresponds to 18×6 subcarriers. The LRU 1500 includes a signal pilot stream that includes 6 pilot subcarriers 52, 54, 56, 58, 60, and 62. Accordingly, the effective number of subcarriers in the LRU 1500 is 102.
FIG. 18 is a block diagram illustrating the configuration example of a transmitter compatible with the multicarrier operation. The transmitter 1600 includes a channel encoder 1608, a modulator 1612, a data segmentation section 1616, a segment mapping section 1620, and a set 1624 of k subcarrier mapping/IFFT sections, and outputs a set 1626 of k RF carriers. The value of the number k of RF carriers is predetermined. Here, a specific subcarrier mapping/IFFT section is provided to correspond to a specific RF carrier. For example, the first subcarrier mapping/IFFT section 1-1624a corresponds to the RF carrier 1-1626a, and the k-th subcarrier mapping/IFFT section k-1624b corresponds to the RF carrier k-1626b. 
In the transmitter 1600, the channel encoder 1608 encodes the PHY PDU 1606 entered as input data. The channel encoder 1608 performs encoding by a turbo code through a CTC (Convolutional Turbo Coding) Encoder, and generates systematic bit streams A and B and parity bit streams Y1/Y2 and W1/W2. Further, the channel encoder 1608 separates the systematic bit streams and the parity bit streams into respective subblocks A, B, Y1, Y2, W1, and W2, and performs interleaving of the respective subblocks in sections of bits through subblock interleavers. Thereafter, the channel encoder 1608 performs interlacing of the subblocks of the parity bits, which alternately arranges bits in Y1 and Y2, and W1 and W2, and selects and outputs bits according to the coding rate of the transmission data.
Next, the transmitter 1600 generates modulated symbol sequence 1614 by performing modulation of the encoded data 1610 of the output of the channel encoder 1608 using a predetermined modulation technique such as 16 QAM or the like according to the MCS through the modulator 1612. Then, the data segmentation section 1616 performs data segmentation that divides the modulated symbol sequence 1614 into predetermined blocks, and the segment mapping section 1620 performs mapping of the divided segments on data blocks 1618. Accordingly, the respective data blocks 1618 are allocated with RF carrier 1 to RF carrier k. Next, the subcarrier mapping/IFFT sections 1624a to 1624b that correspond to the respective RF carriers generate transmission data of the respective RF carriers of 1-1626a to k-1626b by performing a process of mapping the transmission data onto the subcarriers and an IFFT process. By the above-described operation, the transmission data of the multicarrier is generated and output.